Typically, accessories are attached to weaponry, such as firearms, to enhance the use of the weapon or the accessibility of the attached accessory. Usually, the accessories are attached to a mounting bracket or rail, such as a Picatinny rail, which provides standardized fittings for a variety of accessories. One of the most commonly attached accessories is the Harris bipod, which has long been known for use with benchrest guns, military sharpshooter guns and any gun requiring a secure, calm support for releasing a precision shot. Many marksmen have Harris bipods and almost every gun can be equipped with one. However, Harris bipods are not readily attachable to a Picatinny rail, thus require additional components to attach to a weapon.
A conventional Harris bipod has two long, padded support surfaces that are slightly tilted towards the horizontal mid-line. The bipod further includes two mainly vertical, powerful fingers, which lie adjacent to each other in the transverse direction. The top ends of the fingers each have a pin arranged between the support surfaces. Using a knurled head screw, the fingers can be moved upward or downward. The upward motion moves the fingers apart, against the force of a spring, while the downward motion moves the fingers into a slotted piece, which pushes both the fingers and the pins apart and makes it impossible to separate them.
When a Picatinny rail is not used, a counter surface that is located on the front shaft of the weapon is exposed. The counter surface is located on both sides of the front shaft and is symmetrical to the longitudinal axis of the front shaft. A block, which has a transverse bore hole, sits between the counter surfaces. The block can, for example, sit on a pusher, which is inserted onto a central, horizontal, embedded dove-tail longitudinal rail or nut, or the block can, for example, be screwed directly onto the shaft of the firearm.
When attaching the bipod, the fingers are pushed upward and apart against the force of the spring until the pins are located on both sides of the transverse bore hole of the block. The fingers are then released so that the pins engage with the transverse bore hole. Then the knurled head screw is pulled, whereby the fingers are moved downwards with the help of a lever, in turn pulling the block and counter surfaces downward until contact surfaces and counter surfaces reach full bearing.
An advantage to the Harris bipod is that it can be removed when not in use and only needs to be attached when needed. This allows a marksman to have one bipod that he can use with several weapons. However, one disadvantage is that, for stability reasons, the block must always be securely attached to the weapon. Disassembling the block could damage the threads that mount the block to the weapon. In addition, disassembling the block requires tools and specialized skills. For example, a gunsmith should perform the retooling of a gun for the attachment of the block used to attach a bipod. Clean attachment of the block, so as to not damage the threads, requires technical expertise that a hobbyist does not have. Thus, as a general rule, the protruding block remains on the weapon, where the block is obstructive, until the bipod is attached.
When attaching a bipod to a firearm, the bipod is normally attached as far forward on the firearm as possible. But sometimes a marksman's surroundings can make another attachment point desirable. Also, it may be desirable to position another device such as laser range finder in front of the bipod. However, the essential permanency of the block renders these arrangements impossible for constructional reasons.
More recently, the attachment of other accessories or add-on devices (e.g., sights, laser range finders, night target devices, spotlights, additional hand grips, etc.) has become increasingly important. Consequently, the aforementioned mounting rails (Picatinny or Weaver rails), which are special, projecting, relatively wide rails, are attached to the front side of all types of weapons and even on the bottom side of the shaft or hand guard. New firearms may come equipped with such rails, and old firearms may be retrofitted with the rails. Though these rails are relatively wide and somewhat long, the rails do not hinder movements of the body and do not get stuck in shrubbery, etc.
Accessories that have engagement projections or threads can be easily mounted to a weapon with a mounting rail. Further, if the projections are movable, the projections can be repositioned to guarantee a secure fit of the accessory on the mounting rail, whereby slipping along the mounting rail is rendered impossible.
If the aforementioned bipod is to be mounted to a weapon with these mounting rails, a block can be placed on the bottom side of the mounting rail, i.e., attached below the barrel. However, the aforementioned disadvantages caused by a protruding block must be taken into consideration. For example, with the protruding block on the front of the mounting rail, no other device can be pushed onto the mounting rail.